Field of the Invention
The present invention relates to an X-ray apparatus for diagnosis use and, more particularly, to an X-ray television apparatus for picking up a fluoroscopic image by using one image pick-up tube.
Diagnosis using an X-ray image, which is very effective for early detection of a disease, has frequently been conducted. For example, a fluoroscopic and radiographic apparatus is used for picking up such an X-ray image, and the position and the state of the portion being picked up are observed in a fluoroscopic monitoring mode with a small X-ray dose prior to radiographic imaging, and then the image is radiographically picked up, namely, fixed with increased X-ray dose at the desired position and timing.
Fluoroscopy is largely divided into the following three methods:
(1) simple fluoroscopy for directly observing a fluorescent screen,
(2) X-ray II fluoroscopy for directly observing an X-ray image intensifier (hereinunder referred to as "X-ray II") outputting surface, and
(3) X-ray TV fluoroscopy for observing an X-ray image picked up by a television camera through a TV monitor. Among these, X-ray TV fluoroscopy is now in frequent use because it enables observation in a daylight room and remote control and, in particular, X-ray II -- TV camera systems which can produce a light image at a small X-ray dose is most frequently used.
Such apparatuses for carrying out fluoroscopy through a TV camera, namely, X-ray television apparatuses are described in, for example, Japanese Patent Application Laid-Open Nos. 58-163343 (1983) and 62-287597 (1987). These apparatuses are further provided with an A/D converter for converting a video signal into a digital signal and a memory for storing the thus-obtained digital signal, thereby enabling digital radiography.
The above-described X-ray television apparatuses using an X-ray II and a TV camera have the following problems together with the above-described advantages:
(1) Since an X-ray II is used, the visual field is narrow and it is difficult to enlarge the visual field.
(2) Since an X-ray II is very expensive, the apparatus also is expensive.
As inexpensive X-ray -- TV fluoroscopy , a system of picking up the fluorescence emitted from a fluorescent screen may be considered. However, since the luminance of the fluorescent screen is lower by about two figures than an X-ray II, a system sufficed with an X-ray dose as small as an X-ray II has not been realized.